              (satisfies? ICounted other)
              (== (count coll) (count other)))
       (let [pairs (hamt/pairs h)
-              len   (.-length pairs)]
+            len   (alength pairs)]
           (loop [i 0]
             (if (< i len)
               (let [pair (aget pairs i)

  (-invoke [coll k]
    (-lookup coll k))

  ;; TODO: IKVReduce

  IReduce
  (-reduce [coll f start]
    (throw "-reduce on a map: stub"))

  IPrintable
  (-pr-str [coll]
    (let [pairs (hamt/pairs h)
          len (alength pairs)]
      (loop [i 0
             r "{"]
        (if (< i len)
